What is the treatment for metastases to the spine?

Treatment for Spinal Metastases

Radiotherapy is the first-line treatment for symptomatic spinal metastases when adequate radiation dose can be delivered, with stereotactic body radiation therapy (SBRT) offering superior local control (~90% at 1 year) and pain relief compared to conventional external beam radiotherapy. 1

Initial Diagnostic Approach

Obtain full spinal column MRI with both T1- and T2-weighted sequences immediately when spinal metastases are suspected—this is the only imaging modality that adequately demonstrates spinal metastases and epidural compression. 1 The urgency depends on clinical presentation:

• Local back pain only: MRI within 2 weeks 1
• Unilateral radicular pain: MRI within 1 week 1
• Progressive radicular deficit (>7 days): MRI within 48 hours 1
• Rapid progressive deficit (<7 days): MRI within 24 hours 1
• Suspected metastatic epidural spinal cord compression (MESCC): MRI within 12 hours, treatment within 24 hours 1

Do not rely on conventional x-rays, CT scans, or bone scintigraphy—these cannot exclude spinal metastases. 1

Treatment Selection Algorithm

Step 1: Assess Spinal Stability and Neurological Risk

Use the Spinal Instability Neoplastic Score (SINS) to stratify patients: 1

• SINS ≤6 (stable): Proceed with non-surgical management 1
• SINS 7-12 (potentially unstable): Multidisciplinary consultation required 1
• SINS ≥13 (unstable): Surgery indicated 1

For long bones, use Mirels' score (≥9 indicates high fracture risk). 1

Step 2: Determine Primary Treatment Modality

Radiotherapy is preferred when: 1

• Patient has adequate performance status for radiation
• No mechanical instability present
• No prior radiation to the same site (or SBRT available for reirradiation)
• Life expectancy allows time for radiation effect

Surgery is preferred when: 1

• Life expectancy ≥3 months
• Spinal instability present (SINS ≥13)
• Recurrence/progression after prior radiotherapy where repeat radiation not feasible
• Neurological deterioration despite radiotherapy and corticosteroids
• Limited area of damage/obstruction amenable to surgical approach

For MESCC-induced neurological deficits, surgery and radiotherapy are equivalent options—the choice should be made through multidisciplinary discussion incorporating patient preference. 1

Systemic therapy as primary treatment is appropriate for highly chemosensitive tumors (multiple myeloma, certain lymphomas). 1

Radiation Therapy Options

De Novo (Previously Unirradiated) Spinal Metastases

SBRT achieves 90% local control at 1 year with ~50% complete pain response, significantly superior to conventional external beam radiotherapy (cEBRT). 1 Common SBRT dose-fractionation schemes include: 1

• 16-24 Gy in 1 fraction
• 24 Gy in 2 fractions
• 24-27 Gy in 3 fractions
• 30-35 Gy in 5 fractions

Conventional palliative radiotherapy (8 Gy single fraction or 20-30 Gy in multiple fractions) provides overall pain response in ~70% but complete response in only 0-20%, with ~20% requiring reirradiation within months. 1

Reirradiation for Previously Irradiated Sites

SBRT for reirradiation achieves 76% local control at 1 year (range 66-90%) with pain improvement in 65-81% of patients, making it the recommended option for recurrent disease in previously irradiated volumes. 1 This represents a substantial improvement over conventional reirradiation (58% overall response, 16-28% complete response). 1

Median survival after reirradiation SBRT ranges from 10-22.5 months, justifying aggressive local therapy. 1

Surgical Considerations

Patients must have life expectancy ≥3 months to be surgical candidates. 1 Surgery provides immediate mechanical stability and rapid pain relief, particularly for: 1

• Mechanical instability
• Pathological fractures
• Spinal cord compression requiring urgent decompression

Modern surgical techniques include minimally invasive approaches, computer navigation, and advanced stabilization materials that reduce morbidity. 2

Adjunctive Treatments

Bone-Modifying Agents

Zoledronic acid is FDA-approved for patients with multiple myeloma and documented bone metastases from solid tumors, used in conjunction with standard antineoplastic therapy. 3 This helps prevent skeletal-related events.

Interventional Procedures

Vertebroplasty/cementoplasty provides rapid pain relief (within 24-48 hours), particularly for mechanical pain from fractures, with 67-74% overall pain response at 6-12 months. 1 This can be combined with radiofrequency ablation for enhanced effect. 1

Critical Safety Considerations

Vertebral compression fracture occurs in 12% of SBRT-treated patients (range 0-22%), with risk factors including: 1

• Significant lytic disease
• Baseline fracture
• Doses >19 Gy per fraction
• High baseline SINS score

Radiation-induced myelopathy occurs in only 1.2% of cases with modern SBRT techniques. 1

Before proceeding with SBRT, consult spine surgery if: 1

• Clinical features suggest MESCC
• Mechanical instability present
• Baseline vertebral compression fracture exists

Common Pitfalls to Avoid

Do not delay MRI imaging—conventional imaging cannot exclude spinal metastases and delays definitive diagnosis. 1

Do not use low-dose conventional radiation (8 Gy single fraction) as definitive treatment for patients with good prognosis—this is associated with higher rates of spinal adverse events including epidural spinal cord compression and neurological deterioration. 1

Do not assume poor prognosis in reirradiation patients—median survival of 10-22.5 months justifies aggressive local therapy. 1

Epidural progression is the most common site of SBRT failure—careful spinal cord delineation and respecting dose constraints are essential. 1